The present invention relates to a method of paving a roadway. More specifically, this method includes choosing a bituminous binder for a chipsealing process based on its Adhesion Index.
Hot applied chipseals commonly are applied to pave or upgrade a roadway. However, one disadvantage with conventional chipseals is pervasive aggregate loss over time.
In an attempt to overcome excessive aggregate loss, aggregate has been precoated with bitumen to increase its adhesion in the chipsealing process. Many bitumen coatings will completely cover the aggregate material. One disadvantage with precoatings is that if too much bitumen is added, the aggregate will stick together and form clumps. Another disadvantage with precoating aggregate is that it is expensive due to the additional materials needed and because handling the precoated aggregate is costly.
Methods to increase the embedment of aggregate in the binder also have been tried. One such method involves applying a thicker layer of bitumen to improve adhesion. One disadvantage of such a method is that this creates additional expense.
Antistripping agents also have been added to bitumen to help the adhesion of aggregate to the bitumen. However, even when using such agents, aggregate loss is still problematic. Another disadvantage of using antistripping agents is that they are costly.
Typically, to ensure maximum adhesion, the chipsealed surface is compacted or rolled. One disadvantage with compaction is that it is an additional step in the paving process increasing the time and cost of the chipsealing process. Further, it requires additional equipment. Still further, even with precoated aggregate, antistripping agents, higher embedment of aggregate, and compaction, excessive aggregate loss still occurs.
In order to overcome these disadvantages, a method of chipsealing a road that provides better aggregate adhesion is desired. This method should provide a way to select a binder for the chipsealing process that has good adhesion.